Magnetically coupled pushbutton switches, exemplified in FIGS. 1–4, normally have an electrically conductive armature 2 that is magnetically held by a magnetic coupler layer 4 in a rest position, as in FIG. 1, spaced from electrical conductors 6 and 7 on a non-conductive substrate layer 8. A user-provided actuation force applied to a crown 10 of the armature (usually stamped sheet metal that is silver plated) causes it to snap free of the magnetic coupler layer and close the electrical conductors by electrically connecting them. Withdrawal of the actuation force allows the magnetic coupler layer to attract the armature back to the rest position, resulting in a reopening of the switch. A non-conductive spacer layer 12 (such as high density foam) is adhesively fixed to the substrate layer, with a cavity 14 in the spacer layer exposing the electrical conductors. The magnetic coupler layer overlies the spacer layer. The armature is magnetically coupled to the bottom of the magnetic coupler layer so that the armature is housed within the cavity in the spacer layer. The armature's crown protrudes through an aperture 16 in the magnetic coupler layer. Typically, a polyester spacer and overlay 18 with suitable graphics overlies the magnetic coupler layer to seal the pushbutton switch and to direct a user as to location and function of the switch.
Magnetically coupled pushbutton switches of the prior art, as shown and described in U.S. Pat. Nos. 5,523,730, 5,990,772, 6,262,646, and 6,556,112, incorporated herein by reference but not limitation, all have an armature piece-part that can travel through a unique pivot/click (FIG. 2/FIG. 3) movement designed to create a very distinct tactile feedback to a switch user. FIG. 2 shows that application of an actuation force 20 causes a heel end 22 of the armature to break away from the magnetic coupler layer 4 and travel to the substrate layer 8 where the feet 24 on the heel end stop (creating an initial tactile feedback) and function as a fulcrum for the armature. FIG. 3 shows that continued application of the actuation force causes a toe end 26 of the armature to abruptly break away from the magnetic coupler layer so that the toe end contacts the substrate layer (creating a final tactile feedback). The exploded view in FIG. 4 shows two commonly used electrical conductor arrangements. The single pole arrangement has the armature's heel end contact a single electrical conductor 6 before the armature's toe end contacts the common electrical conductor 7, so the armature electrically connects them. The double pole arrangement has the armature's heel end contact a pair of electrical conductors, 28 and 29, electrically connecting them, and then the armature's toe end travels into contact with the common electrical conductor 7, thereby electrically connecting all of the electrical conductors to each other.
A common characteristic of most magnetically coupled pushbutton switches is that the armatures only reliably contact the substrate layer in three places, in a stable tripod support configuration. The drawback is that the heel end of an armature must be stable or there will not be a consistent initial and final tactile feedback. If two of the tripod supports are under the feet, which is the case in the prior art, there is only one remaining reliable tripod support location. This third tripod support, which will also be the third reliable contact point, is located at the toe end of the armature. Granted, excessive actuation force will cause more than three places to contact, but the reliability is poor.